EP0086182B1 - Electronic impedance-matched line repeater - Google Patents
Electronic impedance-matched line repeater Download PDFInfo
- Publication number
- EP0086182B1 EP0086182B1 EP83850016A EP83850016A EP0086182B1 EP 0086182 B1 EP0086182 B1 EP 0086182B1 EP 83850016 A EP83850016 A EP 83850016A EP 83850016 A EP83850016 A EP 83850016A EP 0086182 B1 EP0086182 B1 EP 0086182B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- wire
- line
- repeater
- amplifier
- impedance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003321 amplification Effects 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 230000001419 dependent effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 4
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/001—Current supply source at the exchanger providing current to substations
- H04M19/005—Feeding arrangements without the use of line transformers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/54—Circuits using the same frequency for two directions of communication
- H04B1/58—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
- H04B1/587—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa using opto-couplers
Definitions
- the present invention relates to an electronic impedance-matched line repeater for connecting a two-wire line to a subscriber exchange.
- a line repeater has the task of forming a junction between a two-wire line (the two-wire side) and two four-wire sides with the object of subdividing the traffic flow through the line into two one-way paths, (see e.g. IBM Technical Disclosure Bulletin, vol. 16, no. 2, July 1973, pages 495 to 496).
- external line repeaters i.e. such repeaters as are arranged between a subscriber exchange and an outgoing line (a line to the main station)
- there is also desired a very well- defined AC impedance which is in most cases somewhat higher, seen from this side.
- the object of the present invention is to provide an electronic line repeater, particularly an external line repeater, with impedance matching in respect of both AC and DC, as seen from the two-wire side.
- a feed-back loop containing amplifier elements is arranged from the two-wire side of the repeater to the incoming four-wire side, whereby desired DC and AC impedance can be obtained by given values for the selected working point and for the gain of the amplifier elements incorporated in the feed-back loop.
- the invention is characterized by the features set forth in the characterizing portion of claim 1.
- the input terminal to the left forms the two-wire side of the repeater.
- a voltage U 1 appears across this terminal which comprises a direct component (the supply direct voltage) and an alternating component (the speech signals from and out, respectively, the line).
- the two-wire loop contains two resistors R 1 and R 2 having the same resistance, and constituting protective resistances to overvoltages.
- a balanced line amplifier F2 contains a driving stage D which is an operational amplifier circuit and an LED light-emitting diode for galvanic isolation between the two- and four-wire sides, described in the European Patent Application No. 0086183 (published on 17.8.83).
- the LED in the driving stage D is optically coupled to a phototransistor T, the collector-emitter circuit of which is connected to both resistors R1 and R2.
- the phototransistor T can also be connected to a Darlington circuit comprising two transistors, as is illustrated in the application mentioned.
- a feed-back loop is provided, comprising a differential amplifier circuit F1 and a resistor R.
- the circuit F1 has two input pairs, of which one is connected across the input of the two-wire side and thus senses the potential drop U i , the other pair being connected to the output side of the balanced line amplifier F2 and thus senses the potential drop U 2 .
- the four-wire side receiver and transmission paths contain buffer steps OP4 and OP5, respectively, suitably looped operational amplifiers of known design.
- the receiver path buffer step OP4 is connected via the resistor R to the input of the line amplifier.
- the incoming speech signal is denoted u s .
- the following calculations are applicable for the line impedance matching in respect of DC and AC impedance matching.
- the DC resistance on the two-wire side input (DC impedance) is determined by the resistance of the resistors R1 and R2 and also by the selected working point of the transistor T. Assume that the voltage U 2 has a direct component U o2 and that the working point of the transistor T is selected so that its collector-emitter current is ICE, then the DC impedance
- the differential amplifier F1 is assumed to have very high-ohmic inputs and thus does not influence the value of Z dc . Since R 1 +R 2 are constant, the working point of the transistor T can be adjusted so that the desired value of U 02 /I CE is obtained. The transistor T must however operate in its linear range.
- the desired input impedance can be obtained if the amplification F 1 and F 2 in the units F1 and F2, respectively, are selected so that correct negative feed-back gives the desired input impedance.
- the amplification F 1 and F 2 in the units F1 and F2, respectively are selected so that correct negative feed-back gives the desired input impedance.
- the input impedance Z AC for alternating current will thus be:
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Power Engineering (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Amplifiers (AREA)
- Interface Circuits In Exchanges (AREA)
- Telephone Function (AREA)
Abstract
Description
- The present invention relates to an electronic impedance-matched line repeater for connecting a two-wire line to a subscriber exchange.
- A line repeater has the task of forming a junction between a two-wire line (the two-wire side) and two four-wire sides with the object of subdividing the traffic flow through the line into two one-way paths, (see e.g. IBM Technical Disclosure Bulletin, vol. 16, no. 2, July 1973, pages 495 to 496). Particularly with external line repeaters, i.e. such repeaters as are arranged between a subscriber exchange and an outgoing line (a line to the main station), it is desired to have as low-ohmic DC impedance as possible, seen from the line side (two-wire side). Furthermore, there is also desired a very well- defined AC impedance, which is in most cases somewhat higher, seen from this side. In known structures this impedance matching has been solved by accurate and relatively complicated dimensioning of hybrid transformers, e.g. according to the European Patent Application No. 0077351, published on 27.4.83. Impedance matching has been carried out in such cases with the aid of RC components in the hybrid transformer, the hybrid itself having been implemented in the form of a transformer coupling.
- The object of the present invention is to provide an electronic line repeater, particularly an external line repeater, with impedance matching in respect of both AC and DC, as seen from the two-wire side.
- This object is achieved in accordance with the invention, such that a feed-back loop containing amplifier elements is arranged from the two-wire side of the repeater to the incoming four-wire side, whereby desired DC and AC impedance can be obtained by given values for the selected working point and for the gain of the amplifier elements incorporated in the feed-back loop. The invention is characterized by the features set forth in the characterizing portion of claim 1.
- The invention will now be described in detail while referring to the appended drawing, illustrating a circuit diagram of the line repeater in accordance with the invention.
- In the circuit diagram of the Figure, the input terminal to the left forms the two-wire side of the repeater. A voltage U1 appears across this terminal which comprises a direct component (the supply direct voltage) and an alternating component (the speech signals from and out, respectively, the line). The two-wire loop contains two resistors R1 and R2 having the same resistance, and constituting protective resistances to overvoltages. A balanced line amplifier F2 contains a driving stage D which is an operational amplifier circuit and an LED light-emitting diode for galvanic isolation between the two- and four-wire sides, described in the European Patent Application No. 0086183 (published on 17.8.83). The LED in the driving stage D is optically coupled to a phototransistor T, the collector-emitter circuit of which is connected to both resistors R1 and R2. The phototransistor T can also be connected to a Darlington circuit comprising two transistors, as is illustrated in the application mentioned. In accordance with the invention, a feed-back loop is provided, comprising a differential amplifier circuit F1 and a resistor R. The circuit F1 has two input pairs, of which one is connected across the input of the two-wire side and thus senses the potential drop Ui, the other pair being connected to the output side of the balanced line amplifier F2 and thus senses the potential drop U2. The differential amplifier circuit F1 provides an output U3=F1 (U1―U2) and contains three operational amplifiers OP1 to OP3. Both amplifiers OP1 and OP2 sense the potential drops U1 and U2, respectively, and each transmits signals to both inputs of the amplifier OP3. This amplifier subtracts and filters the output signals from the amplifiers OP1, OP2 and gives the output signal u3, which does not contain any DC-component from the two-wire side but only the speech signal component, since a difference signal is formed in the amplifier OP3. The output signal from the amplifier OP3 thus constitutes an amplified speech signal from the two-wire side. This signal is connected via the resistor R to the input of the line amplifier F2.
- The four-wire side receiver and transmission paths contain buffer steps OP4 and OP5, respectively, suitably looped operational amplifiers of known design. The receiver path buffer step OP4 is connected via the resistor R to the input of the line amplifier. The incoming speech signal is denoted us. If low-ohmic output is assumed for the buffer step OP5, as with the output of the final amplifier OP3 (which is the general case for operational amplifiers), the input signal U4 to the line amplifier F2 (which thus only contains the speech signal) is obtained by voltage division between the resistances of the resistors R, i.e. u4=u3/2+u5/2 if the resistors R have the same resistance. The following calculations are applicable for the line impedance matching in respect of DC and AC impedance matching.
- The DC resistance on the two-wire side input (DC impedance) is determined by the resistance of the resistors R1 and R2 and also by the selected working point of the transistor T. Assume that the voltage U2 has a direct component Uo2 and that the working point of the transistor T is selected so that its collector-emitter current is ICE, then the DC impedance
- The differential amplifier F1 is assumed to have very high-ohmic inputs and thus does not influence the value of Zdc. Since R1+R2 are constant, the working point of the transistor T can be adjusted so that the desired value of U02/ICE is obtained. The transistor T must however operate in its linear range.
-
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- For the no-load state:
- 1=0, U1=U2, which gives U3=0 and
- u2=F2. U5/2, where u1, u2 denote the signal magnitudes of U1 and U2 respectively.
-
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- For example, if an AC impedance ZAc=600 ohms is desired and R1=R2=30 ohms, there is obtained according to the above that F1. Fz=18. Assume that F2=0,2 which is a usual value for the coupling factor of an optocoupler, there is obtained F1=90. This amplification of the block F1 is very moderate, and can be achieved without difficulty and be kept constant by suitably selecting the resistors determining the gain.
- By introducing integrating or differentiating networks in a manner known per se, in the operational amplifier block F1, the gain F1 can be made complex, i.e. F1=F1(jw) whereby a complex ZAC may be obtained.
Claims (4)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT83850016T ATE26782T1 (en) | 1982-02-09 | 1983-01-26 | ELECTRONIC LINE AMPLIFIER WITH IMPEDANCE ADJUSTMENT. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE8200741A SE430198B (en) | 1982-02-09 | 1982-02-09 | ELECTRONIC IMPEDANCE CUSTOM LINE TRANSFER |
SE8200741 | 1982-02-09 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0086182A2 EP0086182A2 (en) | 1983-08-17 |
EP0086182A3 EP0086182A3 (en) | 1984-08-15 |
EP0086182B1 true EP0086182B1 (en) | 1987-04-22 |
Family
ID=20345950
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83850016A Expired EP0086182B1 (en) | 1982-02-09 | 1983-01-26 | Electronic impedance-matched line repeater |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0086182B1 (en) |
AT (1) | ATE26782T1 (en) |
CA (1) | CA1195446A (en) |
DE (1) | DE3371151D1 (en) |
SE (1) | SE430198B (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2898165B2 (en) * | 1993-04-16 | 1999-05-31 | シャープ株式会社 | Hybrid circuit |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4181824A (en) * | 1978-10-10 | 1980-01-01 | Bell Telephone Laboratories, Incorporated | Balancing impedance circuit |
FR2462070A1 (en) * | 1979-07-17 | 1981-02-06 | Cit Alcatel | DEVICE FOR SUPPLYING A SUBSCRIBER STATION |
-
1982
- 1982-02-09 SE SE8200741A patent/SE430198B/en not_active IP Right Cessation
-
1983
- 1983-01-26 EP EP83850016A patent/EP0086182B1/en not_active Expired
- 1983-01-26 AT AT83850016T patent/ATE26782T1/en active
- 1983-01-26 DE DE8383850016T patent/DE3371151D1/en not_active Expired
- 1983-02-09 CA CA000421186A patent/CA1195446A/en not_active Expired
Non-Patent Citations (1)
Title |
---|
IBM TECHNICAL DISCLOSURE BULLETIN, vol. 16, no. 4, September 1973, pages 1173-1174, New York, USA M.A. PATTEN: "Electronic hybrid telephone line pack" * |
Also Published As
Publication number | Publication date |
---|---|
SE430198B (en) | 1983-10-24 |
EP0086182A3 (en) | 1984-08-15 |
SE8200741L (en) | 1983-08-10 |
ATE26782T1 (en) | 1987-05-15 |
EP0086182A2 (en) | 1983-08-17 |
DE3371151D1 (en) | 1987-05-27 |
CA1195446A (en) | 1985-10-15 |
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